WO2023117679A1

WO2023117679A1 - Illumination device for illuminating a scene, camera system, and method for illuminating a scene

Info

Publication number: WO2023117679A1
Application number: PCT/EP2022/086128
Authority: WO
Inventors: Stephan Gronenborn
Original assignee: Trumpf Photonic Components Gmbh
Priority date: 2021-12-21
Filing date: 2022-12-15
Publication date: 2023-06-29
Also published as: DE102021134130A1

Abstract

The invention relates to an illumination device for illuminating a scene, said illumination device comprising an array (104) of light sources (106) which are each designed to emit a light beam (108). The illumination device also has a first optical unit (110) and a second optical unit (118), wherein the first optical unit (110) receives the light beams (108) emitted by the light sources (106) and directs them towards the second optical unit (118). The first optical unit (110) is an imaging optical unit that projects the individual light beams (108) into the scene as spots (152) in order to illuminate the scene with a spot pattern, and the second optical unit (118) is an expanding optical unit that partially expands the light beams (108) in order to use the expanded portion of the light beams (108) to illuminate the scene with a substantially homogeneous illumination profile (154) simultaneously with the spot pattern. The expanded portion of the light beams (108) is less than 90% of the light intensity of the light beams (108) emitted by the light sources (106). The invention also relates to a camera system comprising such an illumination device and to a method for illuminating a scene.

Description

Lighting apparatus for illuminating a scene, camera system and method for illuminating a scene

FIELD OF THE INVENTION

The invention relates to a lighting device for illuminating a scene. The invention also relates to a camera system in which such a lighting device is used. Finally, the invention relates to a method for illuminating a scene.

BACKGROUND OF THE INVENTION

[0002] Modern cameras, which are used, for example, for distance measurement, object recognition or gesture recognition, require special lighting profiles. In order to record a two-dimensional (2D) camera image of the scene, for example an object, with a camera, for example a standard camera, flood lighting that is as homogeneous as possible is required that covers the scene with as much illuminated with uniform illuminance. If the camera is used as a three-dimensional (3D) sensor, illumination with a structured light pattern is required, whereby a depth image of the illuminated scene can be obtained by triangulation.

An illumination device of the type mentioned can also be used with a time-of-flight (Time-Of-Flight, TOF) camera. With flood lighting, the full resolution of the camera can be used, but only at limited distances, since the overall performance of the lighting device must be matched to the eye safety required by laser light sources. Using a structured light pattern, also known as a spot pattern, concentrates eye-safe energy into a few pixels, increasing the signal-to-noise ratio on those pixels and thus allowing longer measurement distances, but at the cost of lower resolution. If both illumination profiles can be generated by the illumination device, i.e. homogeneous flood illumination and spot illumination, the TOF camera can measure at different measurement distances. If only one of the two illumination profiles is provided, this limits either the measurement distance or the resolution.

[0004] These special combinations of functions in one and the same

Cameras require either two different light sources that are individually controlled, or one light source that can be switched between flood lighting and spot lighting. Such a lighting device is described in document CN 108332082A. This lighting device combines the two functions of flood lighting and spot lighting, and the lighting device must be switched between flood lighting and spot lighting. The lighting device includes a light source for emitting a light beam, a lens for diverging or converging the light beam, a diffractive optical element for expanding and directing the light beam onto the scene to be illuminated, and a processor to control the light beam. In one embodiment, the lens is a zoom lens and the processor is used to change the focal length of the lens to achieve flood lighting or spot lighting. In further exemplary embodiments, the diffractive optical element has a first diffraction pattern and a second diffraction pattern, wherein the angle between adjacent diffracted light beams is not larger than the acceptance angle of the incident light beam to realize flood illumination. The angle between adjacent diffracted light beams diffracted by the second diffraction pattern is larger than the aperture angle of the incident light beam to realize structured light illumination. The light source comprises a first partial light source and a second partial light source, wherein the processor controls the first partial light source to emit a first partial light beam, and the first partial light beam is replicated and expanded by the diffractive optical element, to achieve flood lighting. An adjustment device controls the second partial light source to emit a second partial light beam, and the second partial light beam is copied and expanded by the diffractive optical element to realize illumination with the spot pattern. The first partial light source and the second partial light source have different properties with regard to the light-emitting surface, the opening angle and/or the amount of light. This known lighting device is therefore structurally complex and therefore expensive, since either movable optical elements, different light sources, diffractive optical elements with different diffraction patterns and/or light beam control are required for the two different lighting profiles of flood lighting and spot lighting.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a lighting device which can simultaneously provide flood lighting and spot lighting for illuminating a scene while being structurally less complex and less expensive.

The invention is also based on the object of providing a camera system with such an illumination device and a method for illuminating a scene.

According to the invention there is provided a lighting device for illuminating a scene, with an array of light sources which are designed to each to emit a light bundle, furthermore with a first optic and a second optic, wherein the first optic receives the light bundles emitted by the light sources and directs them onto the second optic, wherein the first optic is an imaging optic that directs the individual light bundles into the scene projected as spots to illuminate the scene with a spot pattern, and the second optic is expanding optics which partially expand the light beams in order to use the expanded portion of the light beams to illuminate the scene simultaneously with the spot pattern with a substantially homogeneous illumination profile, the expanded portion of the light beams being less than 90% of the light intensity of the light beams emitted by the light sources.

The lighting device according to the invention generates a lighting profile in the scene to be illuminated which is the sum of a substantially homogeneous flood lighting and a spot lighting. Flood lighting and spot lighting are generated simultaneously and directed into the scene without the need for special control of the light sources, light sources with different characteristics, nor movable controlled or switchable optics. How the lighting profile with the simultaneous flood lighting and spot lighting is used by the camera will be described later with reference to a camera system according to the invention.

The first optics of the lighting device is an imaging optics that images the light sources in the scene to be illuminated, which is equivalent to the fact that the individual light beams are projected into the scene as a spot. For example, the first optic can be a converging single lens, but the first optic can also have multiple lenses. The second optic, which is connected downstream of the first optic, serves to generate the flood lighting, which fills the spaces between the individual spotlights in the scene as evenly as possible with light intensity. The uniform light intensity between the spots is lower than the intensity of the spots. For this purpose, the second lens spatially distributes only part of the light energy contained in the light bundles onto the scene. The second optic can be designed as a diffusive, refractive or diffractive optic that partially expands the individual light bundles that come from the first optic. However, not the entire light intensity of the light bundle is expanded, as is the case or desired with standard diffusers, for example, but only a proportion of the light intensity sity of the light beam, so that on the one hand a pronounced spot illumination with higher irradiance in the spots and on the other hand a substantially homogeneous irradiance with lower irradiance between the spots can be realized.

The second optics can, for example, be a transmitting or reflecting diffractive element, for example a diffractive beam splitter. In principle, all types of diffractive elements can be used in the lighting device according to the invention. The second optics can also be refractive optics, for example a scattering element formed from a microlens array, or diffusive optics, for example a scattering element.

The array of light sources can in particular be two-dimensional

array of light sources. The light sources may be laser diodes, particularly vertical cavity surface emitting lasers (VCSELs). The light beam emitted by a VCSEL typically has a circular cross-section in the far field, and the full acceptance angle of the light beam emitted by a VCSEL is typically small, for example less than 20°.

At least the first optics can be integrated into the array of light sources. For example, the light sources can be VCSELs, in which case the first optics, in the case of lasers emitting on the substrate side, can be integrated into the wafer or into the substrate on which the VCSELs are arranged. The second optic can be formed integrally with the first optic.

Preferably, the expanded portion of the second optics is

Light intensity of the light beams is less than 80%, preferably less than 70%, more preferably less than 60%, more preferably less than 50% of the light intensity of the light beams emitted by the light sources.

The lower the deflected or widened from the light beams

The proportion of the light energy of the light bundle is, the more light intensity remains in the spot lighting, which has the advantage that the measuring distance with a 3D camera, e.g. wise a TOF camera, is enlarged. This is particularly useful when capturing 3D objects that are far away. Conversely, the more light intensity is branched off or expanded from the light bundles, the "brighter" the flood lighting, which means that a well-lit 2D image of the scene can be recorded, for example in the case of a camera used as a 2D camera.

[0015]More preferably, the second optic expands the light beams with a maximum expansion angle, which is equal to an angular distance, or an integral multiple thereof, between two light beams minus an opening angle of a light beam.

This configuration differs from standard

Expanding optics, such as diffusers, which scatter all the light beams of the array of light sources into the entire scene.

[0017] In this case, the aforementioned two light bundles are preferably immediately adjacent light bundles.

In this embodiment, the widening angle with which the second

Optics distributes a proportion of the light energy between the spots to be limited to the space between the individual light beams. This achieves the smallest maximum angle of expansion of the individual light bundles.

[0019] If the second optic is a diffractive optic, the diffractive optic is preferably designed in such a way that the angle between intensity maxima of adjacent orders of diffraction essentially corresponds to the aperture angle of a light beam divided by an integer greater than or equal to 1.

In this embodiment, the diffractive optics fans out the individual

Light beams in the individual orders of diffraction, such that the individual orders of diffraction directly adjoin one another or even overlap. The opening angle here is the full opening angle of a light beam. In this context, it is also preferred if the light intensity at the exit of the diffractive optics in the respective zeroth diffraction order is at least 50%, preferably at least 100%, preferably at least 150%, more preferably at least 200% greater than in the Diffraction order with the second greatest light intensity.

This embodiment is a special feature for diffractive optics, since diffractive optics are usually designed in such a way that the zeroth diffraction order is largely suppressed. In the context of the present invention, however, the configuration mentioned is preferred because the zeroth order of diffraction corresponds to the direction of propagation of the portion of the intensity of the light beams for the formation of the spot pattern. This creates the spot pattern in the scene with sufficiently high irradiance, while the first and higher diffraction orders create the flood illumination.

If the second optic is a refractive optic having an array of microlenses, a fill factor of the lenses in the array is less than 100%, preferably less than 90%, more preferably less than 80%, more preferably less than 70 %, more preferably less than 60%, more preferably less than 50%.

[0024] This configuration differs from refractive expanding ones

Optics formed by microlens arrays used with an array of VCSELs. With typical refractive expanding optics based on microlenses, the aim is always to bring the fill factor of the lenses to 100% if possible in order to avoid direct, undeflected transmission through the optics. In contrast, within the scope of the present invention, it is preferred to design the refractive optics with a lower filling factor, such that a significant portion of the light energy is not deflected. In a practical, very simple configuration of the microlens array, this can be achieved by integrating flat or planar areas into the microlens array, for example within each lens, between the lenses, or by replacing some of the lenses with a flat or planar area . The flat areas should be large enough to minimize diffraction at openings formed by the edges of the flat areas. The flat areas should therefore dimensions are of the order of several wavelengths of the light emitted by the light sources.

According to the invention, a camera system is provided with a

Camera having an image sensor, and an illumination device according to one or more of the above configurations, wherein first pixels of the image sensor record the part of the scene illuminated with the essentially homogeneous illumination profile and second pixels record the spot pattern projected into the scene.

The majority of the pixels of the image sensor "see" that part of the scene that is illuminated with the homogeneous floodlight of lower irradiance, while a smaller proportion of the pixels "see" the smaller areas of the scene illuminated by the spots with high irradiance be illuminated.

The camera system preferably has a camera controller that is designed to set the exposure time of the image sensor, the camera controller being designed to set a first exposure time in order to record the scene with the essentially homogeneous illumination profile using the first pixels of the image sensor , and a second exposure time, which is shorter than the first exposure time, in order to use the second pixels of the image sensor to record the scene with the spot pattern projected into the scene.

When the image sensor is used with the first, long, or longer exposure time, the first pixels will produce sufficient sensor signal to allow measurement, while the second pixels will be overexposed and excluded from the measurement. Then the camera with the short or shorter exposure time can be used, in which case the first pixels generate essentially no signal or a signal that is too weak and are excluded from the measurement. The second pixels, on the other hand, generate sufficient signal strength and allow measurement over longer distances, for example. The two measurements can then be combined into a complete picture of the scene. If the camera is a standard camera, for example, it is preferred if the camera controller is designed to record a 2D image of the scene from signal values of the first pixels and 3D information from signal values of the second pixels by means of triangulation identify the scene. As previously described, the 2D image is captured with a long exposure time and the 3D information with a short exposure time.

In this case, the camera control is preferably designed to at least partially replace the signal values obtained from the second pixels during the first (longer or longer) exposure time by signal values obtained from the second pixels during the second (shorter or shorter) exposure time to replace.

In this way, a full 2D grayscale image and additionally the

3D information for the positions of the spots in the spot pattern and the scene can be obtained.

The above replacement of the signal values of the second pixels can be weighted with the exposure time and the relative irradiance.

If the camera is a time-of-flight (TOF) camera, the

Camera control preferably designed to obtain a first 3D partial image of the scene from signal values of the first pixels and a second 3D partial image of the scene from signal values of the second pixels, the camera control being designed to combine the two 3D partial images into a complete 3D combine image of the scene.

[0034] In a TOF camera, which is used to record or measure an object at a short distance, the long exposure time results in a 3D image for the first pixels, while the second pixels are overexposed. The image recorded with a short exposure time results in the 3D partial image only for the second pixel, since the first pixel generates a signal that is too weak. By combining the two partial images, a full-resolution 3D image is obtained, similar to a TOF camera that only works with flood lighting. However, if an object to be observed is far away or has high absorption or low reflection, the second pixels result in at least sufficient signal even after a long exposure time, which makes it possible to obtain a 3D image that has a lower resolution, but still provides 3D information even with large measuring distances or objects that only reflect little light back to the camera.

Further according to the invention, a method for illuminating a

Scene provided, with the steps:

emitting, by means of an array of light sources, individual light bundles,

Projecting, by means of a first optic, the light beams as spots into the scene in order to illuminate the scene with a spot pattern, at the same time as projecting the light beams as spots, partially expanding, by means of a second optic, the light beams in order to match the expanded portion of the Light beams to illuminate the scene together with the spot pattern with a substantially homogeneous illumination profile, wherein the expanded portion of the light beams is less than 90% of the total intensity of the light beams.

The method according to the invention has the same advantages and refinements as the lighting device according to the invention, as described above and as will be described below.

[0037] Further advantages and features result from the following

description and the attached drawing.

It goes without saying that the features mentioned above and to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are illustrated in the drawings and will be described in more detail below with reference to them. Show it:

FIG. 1 shows a basic sketch of an illumination device which has an array of light sources and a first optical system;

FIG. 2 shows a basic sketch of the lighting device in FIG. 1, additionally with a second optical system;

FIG. 3 shows a basic sketch of the lighting device in FIG. 1 to explain the angular spacing between light bundles emitted by the light source and their opening angle;

FIG. 4 shows a basic sketch of the lighting device in FIG. 2, the second optic being a diffractive optic;

FIG. 5a) and b) a top view and a side view of a second optic which is a refractive optic;

FIG. 6 shows a schematic diagram of an illumination device with which a scene is illuminated simultaneously with a spot pattern and with an essentially homogeneous illumination profile;

FIG. 7 shows a front view of a lighting profile;

FIG. 8 shows a basic sketch of a camera system with a camera and an illumination device; and

FIG. 9 shows a flow chart of a method for illuminating a scene.

In the figures, the same or comparable elements are provided with the same reference symbols throughout. With reference to FIGS. 1 and 2, two lighting devices are first described with which a scene can be illuminated either only with a spot pattern or only with a substantially homogeneous illumination profile without a spot pattern.

Fig. 1 shows an illumination device 100 for illuminating a

Scene 102. The lighting fixture 100 includes an array 104 of light sources 106 . The schematic drawing in FIG. 1 shows three light sources 106 by way of example. However, it is understood that the array 104 can have a large number of light sources 106, for example 100 or more light sources 106. In particular, the light sources 106 can be distributed in a two-dimensional arrangement. The light sources 106 can be laser diodes, in particular vertical cavity surface-emitting lasers (VCSELs), and the same applies to the configuration of an illumination device according to the invention, which is to be described later. The light emitted by the light sources can be in the visible and/or in the near infrared or infrared spectral range. Each light source 106 emits a light bundle 108, the light bundles 108 being represented by a line in FIG.

The lighting device 100 also has a first optical system 110 . The optics 110 are imaging optics that project the individual light bundles 108 into the scene 102 as spots 112 . In other words, the first optics 110 images the light sources 106 in the scene 102 .

In FIG. 1, the irradiance E along the scene 102 is illustrated in an upper diagram. Essentially all of the energy of the light emitted by the light sources 106 is contained in the spot pattern, and the irradiance E in the area of the spots 112 is correspondingly high. In areas 116 between the spots 112 there is no or almost no light energy. With an illumination profile with which the scene 102 is illuminated with individual, separated spots 112, a 3D image can be recorded by means of a camera, even at greater distances between the scene 102 and the camera, but with a low resolution. [0045] FIG. 2 shows the lighting device 100 from FIG. In the example in FIG. 2 , the first optic 110 can also be absent. The second optic 118 is an expanding optic that, in contrast to the invention, scatters all the light energy contained in the light beams 108 evenly throughout the scene to be observed, so that the scene 102 is illuminated with a homogeneous illumination profile 120, as in the upper diagram illustrated in FIG. As a comparison of FIG. 2 with FIG individual spots 112 according to FIG. 1. With a homogeneous illumination profile 120 as illustrated in FIG. 2, a 2D image can be recorded by a camera.

For example, if a standard camera both as a camera

If 2D images and 3D images are to be recorded, both illumination profiles, i.e. both the spot pattern according to Fig. 1 and the essentially homogeneous illumination profile according to Fig. 2, are required. This can be realized in that the lighting device 100 is switched between the two types of lighting, for example by the second optics 118 being alternately introduced into the beam path and brought out of it again. However, this is associated with additional structural effort. The following describes how it can be made possible for the scene 102 to be illuminated simultaneously with a spot pattern according to FIG. 1 and a substantially homogeneous illumination profile according to FIG. 2 without having to switch the device, movable optical elements or different light sources 106 in the array 104 needs.

In principle, this is achieved according to the invention in that the individual light bundles are partially expanded, ie a proportion of the light energy contained in the light bundles is spatially distributed or fanned out, in particular is broken, scattered or diffracted, so that on the one hand a pronounced spot pattern is obtained remains, otherwise the areas in the scene between the spots 112 are illuminated with a sufficient irradiance. FIG. 3 again shows the lighting device 100 according to FIG. 1, the first optics 110 being illustrated only as a line for the sake of simplicity. The light bundles 108 are shown in FIG. 3 with their opening angle given by the type of light sources 106 . In the case of VCSELs as light sources 106, the natural opening or divergence angle is a few degrees, for example in a range from approximately 12° to 15°. The first optics 110 converges the individual light beams 108, which propagate downstream of the first optics 110 with an opening angle α, which is also referred to as the spot size angle. The individual light bundles 108 are separated from one another by an angular distance y. While FIG. 3 is only a two-dimensional representation, it should be understood that the opening angle a is taken in two mutually perpendicular directions and the angular distance y is also taken in two mutually perpendicular directions in the case of a two-dimensional array 104, with the opening angle a and/or the angular distance y can be different in the two mutually perpendicular directions.

In order to generate an illumination profile in the scene 102 that is simultaneously or in total a spot pattern according to FIG. 1 and a substantially homogeneous illumination profile according to FIG Light bundle 108 receives from the first optics 110, deflects only a proportion of less than 90% of the intensity of the individual light bundles 108 from their direction of propagation, which are illustrated in Fig. 3 with arrows 124, into the respective space between the light bundles 108. Preferably, the deflected portion of the light intensity of the light bundles is less than 80%, preferably less than 70%, more preferably less than 60%, more preferably less than 50% of the light intensity of the light bundles 108 emitted by the light sources 106. The second optics 118 only has to expand one portion of the light intensity of each of the light beams with a maximum expansion angle 3, which is substantially equal to or greater than the angular distance y between two light beams 108. In general, regardless of the type of second optics, preferably 3 > y • i, where i is a integer is greater than or equal to 1. The flare angle θ refers to the full width at half maximum (FWHM) of the intensity of a light beam 108 expanded by the second optics 118 108a is illustrated with broken lines 128 in FIG. The maximum angle θ can be minimized if the angle θ is taken between two immediately adjacent light beams 108 .

This is explained using an example. Suppose the field of view of a camera is 60° x 45°, and this field of view is to be filled with 20 x 15 spots with a spot opening angle (spot size angle) a of 0.5°. The angular distance y between immediately adjacent spots is then 3° in both mutually perpendicular directions (60720 spots=3° or 45715 spots=3°). The second optics 118 can then have a two-dimensional widening pattern with a 3° full opening angle at half the maximum intensity, or a multiple thereof for improved homogeneity.

[0051] In order to achieve this, the second optics 118 can be a diffusive, refractive or diffractive optic.

4 shows the case where the second optics 118 is a diffractive optics, for example a diffractive beam splitter, which splits the individual light bundles 108 into a plurality of light bundles by diffraction. The diffractive optics preferably generates N defined diffracted beams in N orders of diffraction (excluding the zeroth order of diffraction) of the same intensity as possible, preferably has a defined maximum order of diffraction or a defined maximum diffraction angle 0, while the light intensity preferably drops rapidly beyond the maximum order of diffraction. In the example in Fig. 4, the maximum diffraction order is +2 and -2, respectively, and N is thus 4. The maximum diffraction angle 0 is then the full angle between the maximum diffraction orders. The maximum diffraction angle can be the angular distance y between adjacent light bundles 108 minus the aperture or spot size angle a, where in particular 0=yi-a can be where i is an integer. The widening angle 0 is preferably obtained as 0=0+a. A maximum angle δ between the different orders of diffraction is preferably of the order of magnitude of the opening angle or spot size angle α, which is 0.5° in the above example, so that the individual diffracted images of the spots are directly next to one another. border or even overlap. The maximum angle δ between the diffraction orders can also be smaller, such that the images of the individual spots overlap. Very good results are obtained when the maximum angle δ between the diffraction orders corresponds to the acceptance angle (spot size angle) α divided by an integer, ie δ = α/j, where j is an integer.

The second optics 118 can also be refractive or diffusive optics, which in the example mentioned above widens the respective light bundles with a widening angle of 3° in both mutually perpendicular directions.

[0054] Both in the case of a diffractive optics and a refractive or diffusive optics, the second optics 118 is preferably designed in such a way that a significant proportion of the light intensity of each light bundle 108 is not diffracted or not scattered. In other words, in the case of diffractive optics as second optics 118, these are designed such that the light intensity at the exit of the diffractive optics in the zeroth diffraction order is at least 50% greater than in the diffraction order with the second greatest light intensity. Preferably, the light intensity at the exit of the diffractive optics in the respective zeroth diffraction order is at least 100%, preferably at least 150%, more preferably at least 200% greater than in the diffraction order with the second greatest light intensity. The same applies if the second lens 118 is a diffuse lens. In this case, too, it is preferred if the undeflected intensity at the exit of the diffusive optics is greater in the above-mentioned orders of magnitude than in the scattered directions.

A diffractive optics can be transmissive or reflective diffractive

be trained optics. The diffractive optics can be in the form of line gratings, perforated gratings, Echelle gratings, hologram gratings, etc., provided the diffractive optics diffracts less than 90% of the light intensity from the light bundles into the first, second and other diffraction orders, as described above.

5a) and b) show a second optics 118, which is designed as a refractive optics. In this example, the second optics 118 are in the form of an array 128 of microlenses 130 . In contrast to typical microlens-based optics in which it is desired to bring the fill factor of the lenses close to 100% in order to avoid scattering losses and in particular direct, undeflected transmission through the optics, the array 128 of microlenses 130 is intended to have certain areas 132 of the array 128 do not deflect or scatter the respective light beam so that a significant portion of the light energy is not expanded. The fill factor of the lenses in the array is preferably less than 90%, more preferably less than 80%, more preferably less than 70%, more preferably less than 60%, more preferably less than 50%. 5a) and b) show as a simple example that flat areas 134 are integrated into the array, for example, within some or all of the lenses or between the lenses. Areas that do not widen can also be realized by omitting part of the lenses in order to achieve a degree of filling of the array with lenses of well below 100%, for example 50%. The flat areas 134 should be large enough so that diffraction losses caused by fringes are minimized. In other words, apertures created by the flat areas should have a size on the order of several wavelengths of the light emitted by the light sources.

A diffusive optics as the second optics 118 can be a scattering

Pane, for example a pane with a rough surface, or frosted glass, with areas also present here that have no scattering effect, so as not to scatter a significant proportion of the intensity of the light beams 108 in order to maintain a pronounced spot pattern in the illumination profile.

6 shows a lighting device 100 that combines the aspects described above. The lighting device 100 has the array 104 of light sources 106 which each emit a light bundle 108 . The light bundles 108 are projected into the scene 102 by the imaging first optics 110 . The second optics 118 receives the light bundles 108 from the first optics 110 and expands a proportion of less than 90% of the light intensity of the individual light bundles 108 . The second optics 118 are designed as described above, for example as diffractive, refracting or scattering optics with the properties described above. The lighting profile 150 resulting in the scene 102 also contains a spot pattern of spots 152 and at the same time an essentially homogeneous illumination profile 154. In other words, the illumination profile 150 is the sum of the spot pattern 152 and the essentially homogeneous illumination profile 154. The individual spots 152 have a greater intensity or irradiance E in the scene 102 than the im Substantially homogeneous illumination profile 154. The advantage of the lighting device 100 is that the light sources 106 do not have to differ from one another or be operated differently, nor do optics such as the first optics 110 and/or the second optics 118 have to be relocated or brought into or out of the beam path.

Fig. 7 shows the lighting profile 150 in a front view with the

Spots 152 and the essentially homogeneous lighting profile 154.

Fig. 8 shows a camera system 200, the lighting device

100 according to one or more of the embodiments described above and a camera 202 . The lighting device 100 illuminates the scene 102 with the lighting profile 150, which simultaneously contains a spot pattern of spots 152 and a substantially homogeneous lighting profile 154 with a lower illuminance than the spot pattern, as described above.

The camera 202 has an image sensor 204 . FIG. 8 shows an enlarged section of the image sensor 204 in a plan view. The camera 202 also has a camera controller 206 .

The camera 202 captures the scene 102 corresponding to the lighting profile

150 is lit up. First pixels 208 of image sensor 204, which are not hatched in the enlarged detail in FIG. 8, see the larger part of the scene illuminated with essentially homogeneous illumination profile 154. On the other hand, second pixels 210, which are hatched in the enlarged detail of the image sensor 204 in FIG. 8, see the smaller part of the scene into which the spot pattern with the spots 152 is projected. The camera controller 206 is designed to set the exposure time of the

Adjust image sensor 204. In this case, the camera controller 206 is designed to set a first exposure time Ti in order to record the scene 102 with the essentially homogeneous illumination profile 154 using the first pixels 208 of the image sensor 204 . The camera controller 206 is also designed to set a second exposure time T2 that is shorter than the first exposure time Ti in order to record the scene 102 with the spot pattern with the spots 152 projected into the scene using the second pixels 210 of the image sensor 204 .

When the first (longer) exposure time Ti is set, the first pixels 208 will give a sensor signal sufficient in terms of signal-to-noise ratio to allow measurement, while the second pixels 210 will be overexposed and from the measurement be excluded. The camera can then be used with the second (shorter) exposure time T2, in which case the first pixels 208 then generate no image signal or an image signal that is too weak, since the essentially homogeneous illumination profile 154 has a comparatively low irradiance E. The first pixels 208 thus do not contribute to the measurement and are excluded from it. The second pixels 210 result in a good signal strength with the short exposure time T2 and allow measurement even at greater distances to the scene 102. Both measurements, i.e. the measurement with the short exposure time and the measurement with the long exposure time, can then be combined into a complete image of the scene 102 can be combined.

The camera 202 can, for example, be a standard camera or a

Time of flight (TOF) camera.

In the event that the camera 202 is a standard camera, with the

Camera 202 when setting the shorter exposure time T2, the part of the scene 202 illuminated with the spot pattern can be recorded, with the camera control then determining 3D information about the scene 102 from the signal values of the second pixels 210 by means of triangulation, ie a depth image of the scene with a resolution corresponding to the density of the spots in the scene 102 . If the longer exposure time is set, the camera 202 can capture a conventional 2D image using the first pixels 208 are captured while the second pixels 210 are overexposed. The signal values of the second pixels 210 can be replaced in one processing step with the signal values of the second pixels for the short exposure time T2, it being possible for the replacement to be weighted with the exposure time and the relative irradiance. Overall, a full two-dimensional image, for example a grayscale image, and additionally the three-dimensional information for the positions of the spots 152 in the spot pattern of the lighting profile 150 can be obtained.

When the camera 202 is a time of flight (TOF) camera, a scene 102 close to the camera 202, such as an object close to the camera, can be captured. When the long exposure time Ti is set, a 3D partial image is generated from the first pixels 208, while the second pixels 210 are overexposed and excluded from the measurement. With the short exposure time T2, a 3D partial image results only from the signal values of the second pixel, since the signal values of the first pixel 208 are too low. Combining the two 3D partial images results in a full-resolution 3D image. However, in contrast to a TOF camera that is operated with an illumination device that only provides flood illumination, the camera system according to the invention can also record a remote scene 102, for example an object remote from the camera 202, or an object , which has strong absorption or low reflection, since the second pixels 210 still provide a good signal, at least when the longer exposure time Ti is set. This means that the camera system according to the invention makes it possible to obtain at least one 3D partial image, albeit with a lower resolution, even with larger measuring distances or when capturing scenes that reflect only little illumination light. This is a significant difference from the conventional case that the TOF camera is operated with an illumination device that only provides flood illumination.

In Figure 9 is a flow chart of a method for illuminating a

scene shown. The method has a step S10 according to which individual light bundles 108 are emitted by means of the array 104 of light sources 106 . In a step S12 by means of the first optics 110, the light beam

108 are projected into the scene 102 as spots 152 to illuminate the scene 102 with a spot pattern.

In a step S14, at the same time as the light bundles 108 are projected as spots 152, the light bundles 108 are partially expanded, in particular scattered or diffracted, by means of a second optic, in order to use the scattered or diffracted portion of the light intensity of the light bundles 108 to capture the scene together with to illuminate the spot pattern 152 with a substantially homogeneous illumination profile 154. The scattered or diffracted portion of the light intensity of the light bundles 108 is less than 90% of the total intensity of the light bundles 108.

An illumination profile 150, as shown in FIG. 6, can thus be generated with the method.

Claims

22 claims

1. Lighting device for illuminating a scene, with an array (104) of light sources (106), each designed to emit a light beam (108), furthermore with a first optics (110) and a second optics (118), wherein the first optics (110) receives the light bundles (108) emitted by the light sources (106) and directs them onto the second optics (118), the first optics (110) being imaging optics which the individual light bundles (108) in the scene is projected as spots (152) to illuminate the scene with a spot pattern, and the second optics (118) are expanding optics which partially expand the individual light beams (108) in order to use the expanded portion of the light beams (108) illuminate the scene simultaneously with the spot pattern with a substantially homogeneous illumination profile (154), wherein the expanded portion of the light beams (108) is less than 90% of the light intensity of the light beams (108) emitted by the light sources (106).

2. Lighting device according to claim 1, wherein the expanded proportion of the light bundles (108) is less than 80%, preferably less than 70%, more preferably less than 60%, more preferably less than 50% of the light intensity emitted by the light sources (106). Light beam (108) is.

3. Lighting device according to claim 1 or 2, wherein the second optics (118) expands the light bundles (108) with an expansion angle (3) which is equal to an angular distance (y), or an integer multiple thereof, between two light bundles (108). .

4. Lighting device according to claim 3, wherein the two light beams (106) are immediately adjacent light beams.

5. Lighting device according to one of claims 1 to 4, wherein the second optics (118) is a diffractive, refractive or diffusive optics.

6. Lighting device according to one of claims 1 to 5, wherein the second optics (118) is a diffractive optics, the diffractive optics being designed such that the angle (δ) between intensity maxima of adjacent diffraction orders essentially corresponds to the aperture angle (α) of a light beam ( 108) divided by an integer greater than or equal to 1.

7. Lighting device according to one of claims 1 to 6, wherein the second optics (118) is a diffractive optics, which bends the individual light bundles (108) each with a maximum diffraction angle that is equal to an angular distance (y), or an integer multiple thereof, between two light beams (108) minus an opening angle (a) of a light beam (108).

8. Lighting device according to one of claims 1 to 7, wherein the second optics (118) is a diffractive optics, and wherein the light intensity at the output of the diffractive optics is at least 50% greater in the respective zeroth diffraction order than in the diffraction order with the second highest light intensity.

9. Lighting device according to claim 8, wherein the light intensity at the output of the diffractive optics in the respective zero diffraction order is at least 100%, preferably at least 150%, more preferably at least 200% greater than in the diffraction order with the second greatest light intensity.

10. Lighting device according to one of claims 1 to 5, wherein the second optics (118) is a refractive optics having an array (128) of microlenses (130), wherein a fill factor of the microlenses (130) in the array is less than 100 %, preferably less than 90%, more preferably less than 80%, more preferably less than 70%, more preferably less than 60%, more preferably less than 50%.

11 . Camera system, with a camera (202) having an image sensor (204), furthermore with an illumination device (100) according to any one of claims 1 to 10, wherein first pixels (208) of the image sensor (204) with the substantially homogeneous illumination profile (154) record the illuminated part of the scene and second pixels (210) record the spot pattern projected into the scene.

12. Camera system according to claim 11, further comprising a camera controller (206) which is designed to set the exposure time of the image sensor (204), the camera controller (206) being designed to set a first exposure time in order to work with the first pixels ( 208) of the image sensor (204) to record the scene with the essentially homogeneous illumination profile (154), and a second exposure time that is shorter than the first exposure time in order to use the second pixels (210) of the image sensor (204) to record the scene with the spot pattern projected into the scene.

13. Camera system according to claim 11 or 12, wherein the camera controller (206) is designed to record a 2D image of the scene from signal values of the first pixels (208) and to obtain 3D information about the scene from signal values of the second pixels by means of triangulation determine.

14. Camera system according to claim 12 or 13, wherein the camera controller (206) is designed to at least partially replace the signal values obtained from the second pixels (210) during the first exposure time with signal values obtained from the second pixels (210) during the second exposure time substitute.

15. Camera system according to claim 12, wherein the camera (202) is a time-of-flight camera, and wherein the camera controller (206) is designed to generate a first 3D partial image of the scene from signal values of the first pixels (208) and from signal values of the second pixels ( 210) to obtain a second 3D partial image of the scene, the camera control being designed to combine the two 3D partial images into one 3D image of the scene.

16. A method of lighting a scene, comprising the steps of:

Emitting, by means of an array (104) of light sources (106), of individual light bundles (108),

Projecting, by means of a first optics (110), the light bundles (108) as spots (152) into the scene in order to illuminate the scene with a spot pattern, 25 simultaneously with the projection of the light bundles (108) as spots, partial expansion, by means of a second optics (118), the light bundles (108) in order to use the expanded portion of the light bundles (108) to create the scene together with the spot pattern with an essentially to illuminate a homogeneous illumination profile (154), the expanded proportion of the light bundles (108) being less than 90% of the total intensity of the light bundles (108).